Bro I'm sorry if you misread my post.
For me it's perfectly fine to put one damsel to gauge your water parameters but it's not right to add 3 more onto your existing stock to brawl it out.
Just keep the fish number at one or two max! And if there's aggression remove the aggressor and pass it back to lfs.
Don't add any livestock if that fish died in the process. It simply means your tank is not completely cycled.
Having said this, I'll wish that you understand that prior to addition of the first fish, a proper cycling is still required.